The present invention relates to a thermoplastic welding process and apparatus in which infrared energy is employed as a heat source and pneumatic pressure is used to force one member against another for welding.
There exists a variety of welding techniques for attaching two thermoplastic materials during the manufacture of articles, such as automobile interior panels and the like. Such methods and apparatus include hot plate welding, hot air jet welding, laser welding, and ultrasonic welding. In recent years, the use of infrared welding, such as represented by U.S. Pat. No. 7,006,763, has been employed and represents an improved, relatively inexpensive and easily serviceable system for providing multiple welds coupling one thermoplastic part to another. In such a system, infrared energy from, for example, a halogen light source is focused on a work piece through a compound parabolic concentrator (CPC) or Winston cone and, subsequently, pressure is applied by mechanical means, such as an anvil or punch, for completing the welding process. Cooling air may be supplied for cooling the lamp and work piece. Although such a system provides an improved heat staking or infrared welding of thermoplastic materials, it still requires the use of movable mechanical arms for staking the work pieces together for completing the welding process after the infrared heating cycle.
There remains a need, therefore, for an improved method and apparatus for infrared welding of thermoplastic materials which does not employ mechanical staking or punching devices for completion of the welding process.